This year's Christmas special was the dream team-up I've been fantasizing about for years, yet never really believed would happen. There's always been something compelling about the prospect of seeing Capaldi and Kingston onscreen together. Seeing two old pros trading chops on your favourite show is as good as it gets in my book, and not only did Moffat make it happen, he managed to create one of the show's most emotionally complete episodes to date.

Admittedly, we did have to stagger over a few testicle-grazing hurdles in order to buy that River would've taken so long to recognise the Doctor. Seeing his TARDIS should've been the biggest giveaway ever, but since River's been nicking the Doctor's wheels for centuries, she hardly raised an eyebrow. And after such a high-profile introduction to the Doctor's new sonic screwdriver in 'Hell Bent', you could be forgiven for thinking that the Doctor reverting back to his sonic shades was a purely plot-driven regression. But shouldn't River have noticed the Doctor's genius and signature quippage sooner? Well, maybe. He did say, 'I'm the Doctor' a lot tonight, and was liberally dropping not-so-subtle hints throughout—but the emotional payoff was so good that I'm not sure I even care.

Song has always been a character there to serve the story rather than to exist in her own right. As with Clara, she's spent the bulk of her screen-time shrouded in mystery, which has frequently put her at a disadvantage in terms of character development. Despite being married to the Doctor, their conversations have so often been an exercise in economy and deception. The truth is, River knows a lot about the Doctor, and the Doctor knows a lot about River, and if that knowledge were ever to get out, then the repercussions could be disastrous. Hence their shared and oft used buzzword: spoilers. Spoilers—as all internet savvy peeps know—are the devil's doo-doo, and neither River nor the Doctor are purveyors of Beelzebub's excreta. So for eight years now the Doctor and River have been keeping secrets. Until tonight. Tonight they finally connected, and it was gloriously earnest, natural, and utterly endearing.

In the same way that 'Hell Bent' was a culmination of the Doctor and Clara's relationship, 'The Husbands of River Song' was a celebration of the Doctor and River's tumultuous eight years together on-screen. It's no coincidence that the whole episode was littered with reused dialogue, hat-tips, and revisited moments. Moffat carefully crafted this episode to bring to mind everything we love about River Song, wrapped it in a big fluffy load-of-nonsense plot blanket, and gave her and the Doctor an ending truly befitting their history. If you've ever wondered what River does while the Doctor's away, tonight's story answered your question. She does what all archaeologists do: she incapacitates robots with her sonic trowel, gets repeatedly married, and kills murderers. Let's face it: no sane person ever dug the garden with a fucking paint brush.

Obviously, something of a retcon was required to reconfigure the events of the minisode 'Last Night' to better fit the new narrative, but having Eleven cancel his date with River at the last minute did make a modicum of sense—as did having River reference the Doctor's restricted regenerations in order to explain why she didn't recognise his new face. I loved the way Moffat deceived us into thinking that we were watching a substantially altered River, when we were in fact seeing regular River towards the end of her life. This was a disconsolate River, spending her last days pondering her husband's feelings towards her, deciding that she mattered little, and rejoicing in her lot anyway. That the Doctor was wresting with similar worries was the unexpected icing on the frizzy-haired cake.

The truth is, River's slowly filling diary, and the Doctor's seemingly perpetual absence, was making her doubt her place in his affections. She acknowledged as much in her speech, when she compared the Doctor to a dispassionate sunset—which in turn caused the Doctor to start doubting her feelings towards him. Had there ever been anything real between them, or was she simply using him for his time machine? Seeing both of them so vulnerable gave us such a different perspective on their relationship. I loved seeing the turnaround in the Doctor after he'd revealed his identity. Him saying 'Sweetie' was such a tender moment, as was River imploring the Doctor to save her one last time. Despite both characters' relative strengths, it was refreshing to take a peek at the humanity beneath.

I do like stories where time travel is used to drag out a last moment almost indefinitely. Moffat used it to great effect in 'Hell Bent', and although 'The Husbands of River Song' comes immediately after that story (and one could legitimately ask why Moffat is so soundly flogging his own dead trope horse), I thought it worked well. It allows depressing and hopeful stories to exist simultaneously. Yes, River's fate is still certain, but she at least gets a 24 year stay of execution. Maybe Clara can visit her on Darillium during her own pre-death sojourn—I'm sure they'd have a lot in common. I'm not sure what Big Finish has in store plot-wise for River's up-and-coming adventures next year, but this seems like the sort of situation they could exploit to marvellous effect.

There were so many self-referencing moments wrapped up in the madness, that it'd require an entire essay dedicated to chronicling them to mention them all, but I did enjoy seeing the moment River described in 'Forest of the Dead', where she recalled her last moments with the Doctor ('The towers sang and you cried'.) It was also a nice touch to see the return of River's journal, and witness the moment when the Doctor gave River her sonic screwdriver—all to the accompaniment of Murray Gold's 'Silence in the Library' season four soundtrack. Even the Doctor's last words to River mirrored their earlier dialogue in 'The Impossible Astronaut' ('I hate you', 'No you don't'.) Yet the repetitions and hat-tipping never felt tedious—they were simply decorative baubles on an episode oddly bereft of the usual Christmas schmaltz.

Out of all the romps Moffat has written, this was unquestionably his most full-on, yet he didn't make the mistake of placing its rompiness centre stage—it was simply the engine which drove the character piece sat atop. But despite the plot being secondary, this was such a funny story. The dialogue raced along at an alarming pace, and only improves with multiple viewings: from the Doctor's intense disgust at River's romantic setup, to his grandiose speech over the vastness of the TARDIS' interior, to him gently poking fun at River's post-speech humiliation. I was grinning from ear to ear as they fought over who was going to crash the ship. These were two characters stripped of their usual inhibitions, firing on all 44 cylinders, and loving every minute of pitting their superior mental skills against some of the galaxy's most squishy headed villains.

And the final ten minutes were beautiful—from River's complaint that the Doctor didn't truly understand 'happy ever after', to the Doctor using the Singing Towers of Darillium as a metaphor for himself and River—it was all executed to perfection, and tied a nice little bow on one of Nu-Who's most enduring sagas. Both Capaldi and Kingston did their best work during the episode's dying moments—in fact, I don't think I've seen River look more emotionally engaged. The story pooled everything that River was and is, and showcased it all at once: from her ruthlessness, to her strength, to her passion, to her tenderness—it was all there. And now she's gone. That's two farewells in as many episodes. Some Christmas this turned out to be...

Bits and Pieces:

—I loved River pulling a fez out of her cloth bag and Capaldi's reference to Matt's big chin. It's moments like this that keep the other Doctors alive.

—How did Hydroflax's huge robot body get through the TARDIS' doors?

—Solid, if unspectacular performances from both Greg Davies and Matt Lucas. They were probably underused, but I enjoyed the extra screen-time it gave the Doctor and River, so I ain't complaining.

—All of the visual effects looked beautiful tonight. The Doctor and River falling through the floor after the meteor strike looked fantastic.

—It was so strange to see the Doctor rolling around in the snow laughing. Of course, he has no reason to feel sad, as he can't remember losing Clara.

—After all the faux outrage throughout the earlier seasons about the Doctor not being a sexual creature, how great is it that the show can now pull off a bona fide love story without fandom collectively rending its garments asunder?

—Capaldi's acting is so damned varied. He could so easily have sailed through tonight's episode with a phoned-in performance, but he gave such light and shade to the changing mood of the script, that he made every scene pop.

River: 'Does sarcasm help?'
Doctor: 'Wouldn't it be a great universe if it did?'

River: 'You should know, I have a significant history of escaping.'

River: 'He's the Doctor. He doesn't go around falling in love with people. And if you think he's anything that small, or that ordinary, then you haven't the first idea of what you're dealing with.'

River: 'Go on, scan the whole parsec. He's not here. God knows where he is right now, but I promise you, he's doing whatever the hell he wants and not giving a damn about me—and I'm just fine with that. When you love the Doctor, it's like loving the stars themselves. You don't expect a sunset to admire you back. And if I happen to find myself in danger, let me tell you, the Doctor is not stupid enough, or sentimental enough, and he is certainly not in love enough, to find himself standing in it with me.'
Doctor: 'Hello, Sweetie.'
River: 'You are so doing those roots.'
Doctor: 'What, the roots of the sunset?'
River: 'Don't you dare.'
Doctor: 'I'll have to check with the stars themselves.'

Doctor: 'Times end, River. Because they have to. Because there's no such thing as happy ever after. It's just a lie we tell ourselves because the truth is so hard.'
River: 'No, Doctor, you're wrong. Happy ever after doesn't mean forever... it just means time. Little time. But that's not the sort of thing you could ever understand, is it?'

River: 'I hate you.'
Doctor: 'No you don't.'
---Paul Kelly was once married to River Song, but they divorced in the late 18th century after she stole the Wittelsbach Diamond from his right thigh using a pair of sugar tongs. He will also feature as the Doctor's invisible companion in 2016, but will be killed off three minutes into episode one by a suspiciously heavy acorn.

I liked it quite a bit. The River/Doctor scenes were the highlight. The Doctor doing the 'it's bigger on the inside!' thing was hilarious. However, the rewriting of Last Night didn't sit well with me. Based on Forest of the Dead, it seemed clear that River didn't know that Darillium was her last meeting with a version of The Doctor who remembered her.

"The last time I saw you, the real you, the future you, I mean, you turned up on my doorstep, with a new haircut and a suit. You took me to Darillium to see the Singing Towers. What a night that was. The Towers sang, and you cried. You wouldn't tell me why, but I suppose you knew it was time. My time. Time to come to the library. You even gave me your screwdriver. That should have been a clue."

I also found it kind of distracting how the Christmas town was so obviously the refugee camp from Face the Raven. It seemed like they didn't do much in terms of redressing the set/location to make it seem like a different place. Darillium did look beautiful though.

This episode reminded me a lot of the Firefly episode "Trash". I also revisited the season 6 extras "Night and the Doctor" mini-episodes which act as great companion pieces to this Christmas special, but with Matt Smith.